A number of useful substances are produced in and isolated from the culture broth of various strains of the genus Streptomyces. It is known that Streptomyces myxogenes SF-1130 (identified as FERM-P. 676 or ATCC 31305) produces an antibiotic called SF-1130 substance (see Japanese Patent Publication No. 30393/73). We, the present inventors, already found that the further antibiotic substances active against gram-negative bacteria are produced in the fermentation broth of the microorganism Streptomyces myxogenes SF-1130, and we succeeded in isolating these active substances from the broth and have designated them as SF-1130-x.sub.1 substance and SF-1130-x.sub.2 substance, respectively, as disclosed in the specification of Japanese Patent Application Pre-publication "Kokai" No. 26398/78 or U.S. Pat. No. 4,160,026.
We have made further research on the crude product containing the SF-1130-x.sub.1 and -x.sub.2 substances as obtained from the culture broth of Streptomyces myxogenes SF-1130, and we have now found that the crude product contains a new third ingredient which was not discovered before but exhibits a very weakly antibacterial activity, in addition to the SF-1130-x.sub.1 substance and the SF-1130-x.sub.2 substance. We have now succeeded in isolating this third component from the crude product and have designated this as SF-1130-x.sub.3 substance. We have further noticed that the SF-1130-x.sub.3 substance (hereinafter sometimes abbreviated as the compound of this invention) is an oligosaccharide of weakly basic nature having the physico-chemical properties as mentioned hereinafter which is the novel substance distinct from known closely related species of antibiotics, and that the compound of this invention is highly active to suppress the enzymatic activity of glucosidase.
An object of this invention is to provide a new antibiotic designated as SF-1130-x.sub.3 substance which is useful as an agent for inhibiting the enzymatic activity of glucosidase and as a drug for suppressing an increase in the level of blood sugar in living animals and men which have taken starch and/or sugars. The other object of this invention is to provide a process of producing such a useful substance. Another objects will be clear from the following descriptions.